Supercritical fluid chromatography system

Abstract

Provided is a chiller and system that may be utilized in a supercritical fluid chromatography method, wherein a non-polar solvent may replace a portion or all of a polar solvent for the purpose of separating or extracting desired sample molecules from a combined sample/solvent stream. The system may reduce the amount of polar solvent necessary for chromatographic separation and/or extraction of desired samples. The system may incorporate a supercritical fluid chiller, a supercritical fluid pressure-equalizing vessel and a supercritical fluid cyclonic separator. The supercritical fluid chiller allows for efficient and consistent pumping of liquid-phase gases employing off-the-shelf HPLC pumps. The pressure equalizing vessel allows the use of off-the-shelf HPLC column cartridges. The system may further incorporate the use of one or more disposable cartridges containing silica gel or other suitable medium. The system may also utilize an open loop cooling circuit using fluids with a positive Joule-Thompson coefficient.

What is claimed is: 
     
       1. A method of cooling via a circulator system utilizing the Joule-Thompson cooling effect of a fluid expanding through an expansion device located adjacent a pump head of a chiller pump to cool a refrigerant being pumped by the pump, the method comprising:
 (a) introducing the refrigerant into the circulatory system from a source container holding the refrigerant at ambient temperature, the system comprising an inlet portion, a pressurized portion and an expansion portion; 
 (b) flowing the refrigerant from the inlet portion, comprising the source container connected, via a circuit to the pressurized portion comprising the chiller pump; 
 (c) pumping into the pressurized portion of the system the refrigerant supplied from the inlet portion through the chiller pump with a pump head, the chiller pump pumping at a speed sufficient to keep the refrigerant in continuous circulation through the pressurized portion at: (1) a mass flow rate that is repeatable and proportionate to the operational speed of the chiller pump, (2) a continuous pressure of between 500 psi and 10,000 psi; 
 (d) bringing the pressurized portion into fluid communication with a heat sink to allow heat to pass from a heated component external to the circulatory system, to the heat sink, and to the refrigerant circulating through the pressurized portion; 
 (e) expanding a fluid in the expansion portion of the system through orifices of an expansion device located adjacent to the pump head of the chiller pump, the expansion device cooling the expanding fluid by virtue of the Joule-Thompson effect, the cooled fluid then cooling the pump head that in turn cools the refrigerant flowing into the pressurized portion from the chiller pump to a temperature between −5° C. and −30° C. 
 
     
     
       2. The method of  claim 1 , wherein the refrigerant is selected from the group consisting of hydrogen, nitrogen, argon, carbon dioxide. 
     
     
       3. The method of  claim 1 , wherein the fluid is the refrigerant. 
     
     
       4. The method of  claim 1 , wherein the fluid is the refrigerant and is supplied directly from the source container. 
     
     
       5. The method of  claim 1 , wherein the fluid is the refrigerant and is supplied from an outlet of the pressurized portion of the system. 
     
     
       6. The method of  claim 1 , wherein the refrigerant circulates through the system as a liquid and is maintained at a temperature that is warmer than the triple point temperature for the liquid. 
     
     
       7. The method of  claim 1 , wherein pressurized portion is configured to maintain a mass flow rate of between 10 milliliters per minute and 300 milliliters per minute of the refrigerant within the pressurized portion. 
     
     
       8. The method of  claim 1 , wherein pressurized portion is configured to maintain a mass flow rate of at least 50 milliliters per minute of the refrigerant within the pressurized portion. 
     
     
       9. The method of  claim 1 , wherein the system includes no more than one of said chiller pump. 
     
     
       10. The method of  claim 1 , wherein the system is configured to prevent the refrigerant from evaporating within the pressurized portion. 
     
     
       11. The method of  claim 1 , wherein the system is configured to prevent the refrigerant from forming condensate within the pressurized portion. 
     
     
       12. The method of  claim 1 , wherein the chiller pump is a piston-style positive displacement pump. 
     
     
       13. The method of  claim 1 , wherein the chiller pump is an HPLC—(High Pressure Liquid Chromatography-type) pump. 
     
     
       14. The method of  claim 1 , wherein the chiller pump is configured to pressurize the refrigerant within the pressurized portion to between 1,700 psi and 1,800 psi. 
     
     
       15. The method of  claim 1 , wherein the refrigerant within the pressurized portion is chilled at least 35° C. lower than the refrigerant in the source container. 
     
     
       16. The method of  claim 1 , wherein the expansion device contains at least one inlet orifice for fluid flow and at least one outlet orifice for fluid flow, and the expansion ratio between the at least one inlet orifice and the at least one outlet orifice is equal to or greater than 5 to 1. 
     
     
       17. The method of  claim 1 , wherein the refrigerant in the pressurized portion flows through a chromatographic column configured to allow the refrigerant to pass through a layer of stationary phase media to effectuate the separation of individual chemicals from a chemical mixture. 
     
     
       18. The method of  claim 17 , wherein internal and external pressure on the chromatographic column is balanced such that pressure differential on any wall separating the interior of the column from the exterior of the column is no greater than 200 psi. 
     
     
       19. The method of  claim 5 , wherein the system comprises an open loop cooling circuit configured to allow the fluid to be expelled from the circuit after passing through the expansion device.